Two astronauts from the U.S. space shuttle Endeavor conducted a spacewalk outside the International Space Station Sunday to prepare for future station construction activities and protect the outpost from tiny meteoroids. Their work was part of the continuing evolution of the orbital research laboratory.

For this spacewalk, the U.S. space agency NASA teamed one of its most experienced fliers, Franklin Chang-Diaz, with a novice, French astronaut Philippe Perrin. It is the first of three they will conduct while the shuttle is docked to the station.

Neither had ever been on one before, and shortly after floating into the vacuum, Mr. Chang-Diaz exulted over his first sunrise outside a spacecraft. "This is amazing, incredible, the sunrise! Take some time to look at the sunrise," he said. "It's absolutely spectacular!," agreed Mr. Perrin.

Despite the view, the two spacewalkers had several jobs to complete. First, they attached a large handle on a truss that supports the station's solar energy panels. The handle will be the grappling point when the station's robot arm moves the truss during a future construction job.

The work required Mr. Chang-Diaz to hang upside down from a foot platform like a bat nearly 400 kilometers above the planet. "It's a very strange feeling to fly inverted over the Earth like this," he said.

Next, the spacewalkers temporarily positioned six shields that will be moved next month to protect the Russian module from tiny meteoroids. They are the first of about 25 NASA will install over the next several years.

Then they removed a thermal cover from a platform they will mount on the station's rail car on their next spacewalk Tuesday. The platform will serve as a base for the outpost's robot arm to ride the railway the length of the station for future assembly work.

In addition, the two crewmen inspected a station gyroscope that failed Saturday, an effort that prolonged the planned six-hour spacewalk to seven. The gyroscope is one of four that position and stabilize the outpost. The station can operate with only two, but the failure leaves only one backup gyro until NASA can fly another up on a shuttle early next year.

The shuttle Endeavour docked at the outpost on Friday carrying a new three-member Russian and U.S. station crew to replace the team that has been aboard since December.